The insertion of an erect penis into another man's urethra, which presumably has been stretched over time (typically by way of an active and sometimes aggressive physical training regimen) in order to accommodate said insertion.

Shrimping ain't easy.

Bruce achieved a new level of intimacy by convincing Lance to engage in shrimping, aka the insertion of an erect penis (Bruce) into another man's urethra (Lance), which presumably has been stretched over time (typically by way of an active and sometimes aggressive physical training regimen) in order to accommodate said insertion.

When a guy or a girl or two guys have sexual intercourse. The male ejaculates his load in either the woman's or mans anal cavity. Then the person who has filled up his partners ass with juice sticks a straw up the anus and sucks the cream out to enjoy a warm treat